Vitreous lubricated metal hot-working



nited States PatentO vrranous LUBRICATED METAL HOT-WORKING Paul I. Beliveau, Milford, Conn., assignor to Bridgeport Brass Company, Bridgeport, Co'nn., a corporation of Connecticut No Drawing. Application March 23, 1953, Serial No. 344,239

6 Claims. (Cl. 207-40) This invention relates to the working of hot metal under pressure against a die surface when using a vitreous lubricant between the surface and the metal. With high temperatures and pressures such a lubricant becomes fluid and provides a lubricating film reducing the working pressures otherwise required and protecting the die against the heat of the metal which is heated to render it more malleable.

One of the objects of the present invention is to overcome the problem caused by removing the vitreous lubricant, which is ordinarily glass having a composition adapting it for this kind of use, from the die face against which the hot metal is worked. This is necessary to permit reuse of the die, the vitreous lubricant adhering to the die after the hot-working rarely being suitable for reuse.

The above problem is encountered with particular severity in connection with the extrusion of metal from a metal extrusion press. In this case the vitreous lubricant is used in the form of a body of fiber glass, for example, which is placed in the container liner between the working face of the extrusion die and the forward end of the billet. Enough lubricant is used to assure the provision of a continuous film of lubricant between the working face of the die and the extruding metal, and to this end caution dictates the use of a surplus of the lubricant. The working temperatures and pressures are both quite high with the result that the lubricant remaining in the press, after a billet is extruded, tends to adhere or bond to this face of the die in such a manner as to make removal of the lubricant rather difiicult.

Another object of the present invention is to provide a process for extruding a hot metal billet from a metal extrusion press using the vitreous lubricant, so that the lubricant remaining in the press after an extrusion may be removed from the working face of the die easily and quickly so as not to interfere with the continued operation of the press.

Generally speaking, the present invention includes the positioning of material between the surface against which the metal is worked and the glass lubricant with this material having the characteristic of retarding the bonding or adhering of the vitreous lubricant to the surface. After the working under high temperature and pressure the lubricant is then removed from the surface against which the metal was worked, thus permitting reuse of the surface which is, of course, generally the working surface of a die. This material may comprise a liquid carrying refractory particles and which is coated on the surface prior to positioning the lubricant between this surface and the metal being hot-worked under heavy pressure thereagainst.

One suitable material for preventing the bonding or adhering of the vitreous or glass lubricant, may comprise the ordinary lubricant used on the mandrel of a metal tube extrusion press when operated in the more usual manner not using a glass lubricant, for example, the lubricant used by the brass industry in tube extrusion presses. Such a lubricant ordinarily consists of petroleum oil mixed with graphite. This particular kind of lubricant has been used successfully in practicing the present invention.

As a specific example of the invention, the extrusion of cuprous metal using a glass lubricant is described hereinafter.

Using a conventional extrusion press such as may be found in almost any brass mill, the working cycle starts out with painting the working face of the die with the petroleum oil and graphite mixture normally used on the mandrel of a cuprous metal tube extrusion press. This comprises a mixture of petroleum oil and graphite used in proportions which are well known and familiar to those in the brass industry. The die is then placed in position with the fiber glass body between the dies coated working face and the heated cuprous metal billet which is placed in the container liner. The glass lubricant is used in sufiicient quantity to leave some of it on the dies face at the end of the extrusion push.

Next the ram is advanced so as to extrude the billet after which it becomes necessary to remove and clear the die. With the present invention this is simple because any glass remaining on the working face of the die may be easily pulled off, if it does not remove it self, because the oil and graphite mixture prevents the glass from bonding to the die face, in spite of the high temperatures and pressures encountered in the case of an extrusion press.

In the practice described above the glass layer left on the die is relatively smooth and causes no serious problem even if it is not removed. When not using the oil and graphite mixture, other conditions being similar, the glass layer left on the die face is irregular and spotty or rough, and thus must be removed, its removal involving great difliculty. Thus with the present invention the glass layer may be removed if desired or, with judicious control of the amount of lubricant used for each extrusion push, the glass may actually be left on the working face of the die without introducing an operational problem.

I claim:

1. A process for working hot metal under pressure against a surface with a vitreous lubricant therebetween, including positioning material between the lubricant and surface which retards the bonding of the lubricant to the surface, and working the hot metal under pressure against the surface.

2. A process for working hot metal under pressure against a surface with a vitreous lubricant therebetween, including positioning material between the lubricant and surface which retards the bonding of the lubricant to the surface, and working the hot metal under pressure against the surface, said material comprising a liquid carrying refractory particles and being coated on the surface prior to positioning the lubricant between the metal and the surface.

3. A process for deforming hot metal under pressure against a metal surface, including coating the surface with a mixture of oil and graphite, positioning a vitreous lubricant between the coated surface and the hot metal and deforming the latter against the surface by pressure applied to the hot metal.

4. A process for extruding a hot metal billet from a metal extrusion press, including placing on the working face of the die of the press a material retarding the bonding of vitreous material thereto, placing a vitreous lubricant between the die face and billet in sufficient quantity to leave some of the lubricant on the face after the billet is extruded, and extruding the billet.

5. A process for extruding a hot metal billet from a metal extrusion press, including placing on the working face of the die of the press a material retarding the bonding of vitreous material thereto, placing a vitreous lubricant between the die face and billet in sufficient quantity to leave some of the lubricant on the face after the billet is extruded, and extruding the billet, said material comprising a liquid carrying refractory particles and which is coated on the die face.

6. A process for extruding a hot metal billet from a metal extrusion press, including placing on the working face of the die of the press a material retarding the bonding of vitreous material thereto, placing a vitreous lubricant between the die face and billet in sufiicient quantity to leave some of the lubricant on the face after the billet is extruded, and extruding the billet, said material com- References Cited in the file of this patent UNITED STATES PATENTS 2,038,215 Gillis Apr. 21, 1936 2,112,632 Montgomery Mar. 29, 1938 2,335,933 Goheen et a1. Dec. 7, 1943 2,469,473 Orozco et a1 May 10, 1949 2,538,917 Sejournet et al Jan. 23, 1951 2,630,220 Sejournet Mar. 3, 1953 FOREIGN PATENTS 479,483 Canada Dec. 18, 1951 

1. A PROCESS FOR WORKING HOT METAL UNDER PRESSURE AGAINST A SURFACE WITH A VITREOUS LUBRICANT THEREBETWEEN, INCLUDING POSITIONING MATERIAL BETWEEN THE LUBRICANT AND SURFACE WHIC RETARDS THE BONDING OF THE LUBRICANT TO THE SURFACE, AND WORKING THE HOT METAL UNDER PRESSURE AGAINST THE SURFACE. 